Some good, some bad.
Good: the location, which is walkably close to Ginza. Really good is that it is just a two minute walk to the Kyobashi subway station, which is on the Ginza line. The Tokyo metro system is superb and very easy to navigate if you download one of the several apps for the system.
The rooms are small but clean. Housekeeping is efficient and good. It is generally easy to get a taxi outside the hotel.
Bad: it is bizarre and very inconvenient that there are no drawers in the suite. The bathroom has a good shower but it is a very small space. The front desk staff speak very little English, so communication can be difficult.
The general attitude is very rigid. If you arrive earlier than 3:00pm and want to get to your room they will charge for every hour ahead of 3:00pm. If you ask for a check-out later than 11:00am they will charge for every hour. Most hotels are more accommodating, especially for short periods of time, but not the Mitsui Garden Hotel.